Field of the Invention
This application is generally directed to halons and more particularly, to the use of nitrogen-containing compounds in preparing nonvolatile derivatives of halons and other perhalogenated, ozone-depleting compounds.
Discussion of the Related Art
Halons are generally defined as perhalogenated alkanes, usually containing at least one bromine, while another well-known class of perhalogenated alkanes, freons, contain at least one fluorine, that are often used, among other things, as fire suppressing agents. Yet, because these compounds also damage stratospheric ozone, many have been phased out, while others are in the process of being eliminated altogether. As a result, there are stockpiles of these compounds slated for destruction, which currently occurs by incineration. There have been a limited number of other synthetic processes to convert some halons and freons into various nonvolatiles.
In one of these processes halons react in the gas phase via reductive coupling with methane at elevated temperatures, and halon 1301 (CBrF3) is converted into trifluoromethane, ethylene and HBr; halon 1211 (CBrClF2) is converted into difluoroethane, HCl and HBr. However, this process is run in capital intensive equipment under high purity and extreme conditions.
The reaction of amines with alkylhalides by an SN-2, bimolecular substitution mechanism, has been utilized to prepare a variety of amines and quaternary ammonium compounds. For example,NH3+R1X→R1NH2  1.R1NH2+R2X→R1R2NH  2.R1R2NH+R3X→R1R2R3N  3.R1R2R3N+R4X→R1R2R3R4N+X−  4.
The reaction of amines with halons (perhalogenated alkyls), however, does not easily yield quaternary ammonium compounds due to the instability of the electrophilic, halogenated alkyl byproduct. The resulting alkyl group is predicted to attach to the nitrogen atom, which is then positively charged. However, in the case of halons, the alkyl group is so electrophilic, that it is not stable with this charge. The process does include the initial bimolecular substitution reaction which eliminates either Br− or Cl−.